Does this only work with the "official" ethernet shield. Seems there are some variants out there now and I would like to buy something to test this with as I have lots of industrial Modbus gear at the office.

this is a beginning of IP changer over Ethernet but i didn't manage to implement it fully in to the Modbus code(i have managed to get it to work only by a switch at the beginning of the program before the loop)

But now I have the same problem with the DEBUG flag. It has to be disabled because if it is enables the Arduino hangs.

hgs75 do you get it working with debug flag?

Yes, it works with the debug flag, but now I am using an arduino FIO and a WIZ812, use this diagram to make the conections:http://www.pjrc.com/teensy/td_libs_Ethernet.htmlThe code works fine, I am testing with modscan32, and I still working with the 0018 IDE.